On Wed, 20 Jun 2018 17:47:19 +0900
Byungchul Park <byungchul.p...@lge.com> wrote:
> Get rid of dependency on ->dynticks_nmi_nesting.
This is not a trivial change. Can you please explain the rational and
background in the change log. Add enough context here to know why this
change is needed.
Thanks!
-- Steve
>
> Signed-off-by: Byungchul Park <byungchul.p...@lge.com>
> ---
> kernel/rcu/tree.c | 22 ++++++++++------------
> 1 file changed, 10 insertions(+), 12 deletions(-)
>
> diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
> index deb2508..59ae94e 100644
> --- a/kernel/rcu/tree.c
> +++ b/kernel/rcu/tree.c
> @@ -797,6 +797,11 @@ void rcu_nmi_exit(void)
> return;
> }
>
> + if (!in_nmi()) {
> + rcu_prepare_for_idle();
> + rcu_dynticks_task_enter();
> + }
> +
> /* This NMI interrupted an RCU-idle CPU, restore RCU-idleness. */
> trace_rcu_dyntick(TPS("Startirq"), rdtp->dynticks_nmi_nesting, 0,
> rdtp->dynticks);
> WRITE_ONCE(rdtp->dynticks_nmi_nesting, 0); /* Avoid store tearing. */
> @@ -824,14 +829,8 @@ void rcu_nmi_exit(void)
> */
> void rcu_irq_exit(void)
> {
> - struct rcu_dynticks *rdtp = this_cpu_ptr(&rcu_dynticks);
> -
> lockdep_assert_irqs_disabled();
> - if (rdtp->dynticks_nmi_nesting == 1)
> - rcu_prepare_for_idle();
> rcu_nmi_exit();
> - if (rdtp->dynticks_nmi_nesting == 0)
> - rcu_dynticks_task_enter();
> }
>
> /*
> @@ -944,6 +943,11 @@ void rcu_nmi_enter(void)
> if (rcu_dynticks_curr_cpu_in_eqs()) {
> rcu_dynticks_eqs_exit();
> incby = 1;
> +
> + if (!in_nmi()) {
> + rcu_dynticks_task_exit();
> + rcu_cleanup_after_idle();
> + }
> }
> trace_rcu_dyntick(incby == 1 ? TPS("Endirq") : TPS("++="),
> rdtp->dynticks_nmi_nesting,
> @@ -977,14 +981,8 @@ void rcu_nmi_enter(void)
> */
> void rcu_irq_enter(void)
> {
> - struct rcu_dynticks *rdtp = this_cpu_ptr(&rcu_dynticks);
> -
> lockdep_assert_irqs_disabled();
> - if (rdtp->dynticks_nmi_nesting == 0)
> - rcu_dynticks_task_exit();
> rcu_nmi_enter();
> - if (rdtp->dynticks_nmi_nesting == 1)
> - rcu_cleanup_after_idle();
> }
>
> /*
